Airworthiness Directives; Boeing Model 757-200, -200CB, -200PF, and -300 Series Airplanes

AGENCY:

Federal Aviation Administration (FAA), Department of Transportation (DOT).

ACTION:

Notice of proposed rulemaking (NPRM).

SUMMARY:

The FAA proposes to adopt a new airworthiness directive (AD) for all Boeing Model 757-200, -200CB, -200PF, and -300 series airplanes. This proposed AD would require installation of an automatic shutoff system for the center tank fuel boost pumps, and installation of a placard in the airplane flight deck if necessary. This proposed AD would also require revisions to the Limitations and Normal Procedures sections of the airplane flight manual to advise the flightcrew of certain operating restrictions for airplanes equipped with an automated center tank fuel pump shutoff control. This proposed AD would also require a revision to the Airworthiness Limitations (AWLs) section of the Instructions for Continued Airworthiness to incorporate AWL No. 28-AWL-20 and No. 28-AWL-26. This proposed AD would also require replacement of the fuel control panel assembly with a modified part, installation of two secondary pump control relays for the center tank fuel pumps, other specified actions, and concurrent modification of the fuel control panel assembly. This proposed AD results from fuel system reviews conducted by the manufacturer. We are proposing this AD to prevent center tank fuel pump operation with continuous low pressure, which could lead to friction sparks or overheating in the fuel pump inlet or could create a potential ignition source inside the center fuel tank; these conditions, in combination with flammable fuel vapors, could result in a center fuel tank explosion and consequent loss of the airplane.

DATES:

We must receive comments on this proposed AD by August 23, 2007.

ADDRESSES:

Use one of the following addresses to submit comments on this proposed AD.

• DOT Docket Web site: Go to http://dms.dot.gov and follow the instructions for sending your comments electronically.
• Government-wide rulemaking Web site: Go to http://www.regulations.gov and follow the instructions for sending your comments electronically.
• Mail: U.S. Department of Transportation, Docket Operations, M-30, West Building Ground Floor, Room W12-140, 1200 New Jersey Avenue, SE., Washington, DC 20590.
• Fax: (202) 493-2251.
• Hand Delivery: Room W12-140 on the ground floor of the West Building, 1200 New Jersey Avenue, SE., Washington, DC, between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays.

Contact Boeing Commercial Airplanes, P.O. Box 3707, Seattle, Washington 98124-2207, for the service information identified in this proposed AD.

FOR FURTHER INFORMATION CONTACT:

Judy Coyle, Aerospace Engineer, Propulsion Branch, ANM-140S, FAA, Seattle Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, Washington 98057-3356; telephone (425) 917-6497; fax (425) 917-6590.

SUPPLEMENTARY INFORMATION:

Comments Invited

We invite you to submit any relevant written data, views, or arguments regarding this proposed AD. Send your comments to an address listed in the ADDRESSES section. Include the docket number “FAA-2007-28598; Directorate Identifier 2007-NM-036-AD” at the beginning of your comments. We specifically invite comments on the overall regulatory, economic, environmental, and energy aspects of the proposed AD. We will consider all comments received by the closing date and may amend the proposed AD in light of those comments.

We will post all comments we receive, without change, to http://dms.dot.gov , including any personal information you provide. We will also post a report summarizing each substantive verbal contact with FAA personnel concerning this proposed AD. Using the search function of that Web site, anyone can find and read the comments in any of our dockets, including the name of the individual who sent the comment (or signed the comment on behalf of an association, business, labor union, etc.). You may review DOT's complete Privacy Act Statement in the Federal Register published on April 11, 2000 (65 FR 19477-78), or you may visit http://dms.dot.gov .

Examining the Docket

You may examine the AD docket on the Internet at http://dms.dot.gov , or in person at the Docket Operations office between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays. The Docket Operations office (telephone (800) 647-5527) is located on the ground floor of the West Building at the DOT street address stated in the ADDRESSES section. Comments will be available in the AD docket shortly after the Docket Management System receives them.

Discussion

The FAA has examined the underlying safety issues involved in fuel tank explosions on several large transport airplanes, including the adequacy of existing regulations, the service history of airplanes subject to those regulations, and existing maintenance practices for fuel tank systems. As a result of those findings, we issued a regulation titled “Transport Airplane Fuel Tank System Design Review, Flammability Reduction and Maintenance and Inspection Requirements” (66 FR 23086, May 7, 2001). In addition to new airworthiness standards for transport airplanes and new maintenance requirements, this rule included Special Federal Aviation Regulation No. 88 (“SFAR 88,” Amendment 21-78, and subsequent Amendments 21-82 and 21-83).

Among other actions, SFAR 88 requires certain type design (i.e., type certificate (TC) and supplemental type certificate (STC)) holders to substantiate that their fuel tank systems can prevent ignition sources in the fuel tanks. This requirement applies to type design holders for large turbine-powered transport airplanes and for subsequent modifications to those airplanes. It requires them to perform design reviews and to develop design changes and maintenance procedures if their designs do not meet the new fuel tank safety standards. As explained in the preamble to the rule, we intended to adopt airworthiness directives to mandate any changes found necessary to address unsafe conditions identified as a result of these reviews.

In evaluating these design reviews, we have established four criteria intended to define the unsafe conditions associated with fuel tank systems that require corrective actions. The percentage of operating time during which fuel tanks are exposed to flammable conditions is one of these criteria. The other three criteria address the failure types under evaluation: Single failures, single failures in combination with a latent condition(s), and in-service failure experience. For all four criteria, the evaluations included consideration of previous actions taken that may mitigate the need for further action.

We have determined that the actions identified in this proposed AD are necessary to reduce the potential of ignition sources inside fuel tanks, which, in combination with flammable fuel vapors, could result in fuel tank explosions and consequent loss of the airplane.

Boeing has found that certain failures will result in the center tank fuel pumps continuing to run after the tank has been depleted. Depending on the failure, pump low pressure may not be annunciated, or power may not be removed from the pump when the pump has been commanded “OFF.” Operation of the center tank fuel pump with continuous low pressure could lead to friction sparks or overheating in the fuel boost pump inlet. This condition, if not corrected, could result in a fuel tank explosion and consequent loss of the airplane.

Other Relevant Rulemaking

On September 24, 2002, we issued AD 2002-19-52, amendment 39-12900 (67 FR 61253, September 30, 2002), applicable to all Boeing Model 737-600, -700, -700C, -800, and -900 series airplanes, Model 747 airplanes, and Model 757 airplanes. That AD requires revising the airplane flight manual (AFM) to advise the flightcrew of certain operating restrictions for maintaining minimum fuel levels, prohibits use of the horizontal stabilizer tank on certain airplanes, and prohibits the installation of certain fuel pumps. That AD requires concurrent removal of the currently required AFM revisions and insertion of new AFM revisions, requires installation of placards to alert the flightcrew to the operating restrictions, and prohibits installation of any un-inspected pumps. That AD permits the AFM revision and placard to be removed under certain conditions. Installation of a placard in accordance with paragraph (e) of AD 2002-19-52, amendment 39-12900, is acceptable for compliance with paragraph (h) of this AD.

On November 23, 2002, we issued emergency AD 2002-24-51, amendment 39-12992, applicable to all Boeing Model 737-600, -700, -700C, -800, and -900 series airplanes, Model 747 airplanes, and Model 757 airplanes. (We issued a Federal Register version of AD 2002-24-51 on December 23, 2002 (68 FR 10, January 2, 2003).) That AD requires revising the AFM to require the flightcrew to maintain certain minimum fuel levels in the center fuel tanks and, for certain airplanes, to prohibit the use of the horizontal stabilizer fuel tank and certain center auxiliary fuel tanks. Accomplishing the actions specified in paragraphs (g), (h), (i), and (j) of this proposed AD would terminate the AFM revision specified in paragraph (e) of AD 2002-24-51 for Model 757-200, -200CB, -200PF, and -300 series airplanes that have the automatic shutoff system installed.

Relevant Service Information

We have reviewed Boeing Alert Service Bulletin 757-28A0081, dated February 16, 2006, for Model 757-200, -200CB, and -200PF series airplanes; and Boeing Alert Service Bulletin 757-28A0082, dated February 16, 2006, for Model 757-300 series airplanes. These service bulletins describe procedures for installing an automatic shutoff system for the center tank fuel boost pumps. Installation of the automatic shutoff system includes the following actions:

• In the main flight compartment, installing time delay relays in the P33 and P37 relay panels and installing automatic shutoff fuel test switches at the E2-1 rack stanchion.
• At the P11-3 and P11-4 circuit breaker panels in the flight compartment, adding new circuit breakers and replacing the light plate with a new improved light plate.
• Changing certain wire bundles in the P11-3 and P11-4 circuit breaker panels, in the P33 and P37 relay panels, between the P33 relay panel and the P5 overhead panel, between the P37 relay panel and the P5 overhead panel, and between the P11-3 circuit breaker panel and the P33 relay panel.
• Installing new wire bundles between the P33 relay panel and the test switch at the E2-1 rack stanchion and between the P37 relay panel and the test switch at the E2-1 rack stanchion.

We have also reviewed Section 9 of the Boeing 757 Maintenance Planning Data (MPD) Document, D622N001-9, Revision January 2006 (hereafter referred to as “Revision January 2006 of the MPD”). Subsection G, “AIRWORTHINESS LIMITATIONS—FUEL SYSTEMS AWLs,” of Revision January 2006 of the MPD describes new airworthiness limitations (AWLs) for fuel tank systems. The AWLs include:

• AWL inspections, which are periodic inspections of certain features for latent failures that could contribute to an ignition source.
• Critical design configuration control limitations (CDCCLs), which are limitation requirements to preserve a critical ignition source prevention feature of the fuel tank system design that is necessary to prevent the occurrence of an unsafe condition. The purpose of a CDCCL is to provide instruction to retain the critical ignition source prevention feature during configuration change that may be caused by alterations, repairs, or maintenance actions. A CDCCL is not a periodic inspection. Revision January 2006 of the MPD adds new fuel system AWL No. 28-AWL-20, which is a repetitive inspection of the automatic shutoff system for the center tank fuel boost pumps to verify functional integrity.

We have also reviewed Boeing Alert Service Bulletin 757-28A0105, Revision 1, dated April 2, 2007, for Model 757-200, -200CB, -200PF, and -300 series airplanes. This service bulletin describes procedures for replacing fuel control panel assembly part number (P/N) 233N3206-( ) (equipment number M10055) with a modified fuel control panel assembly, installing two secondary override pump control relays for the center tank fuel pumps in the P33 and P37 relays panels, and doing other specified actions. The other specified actions include the following:

• Changing the W2066 wire bundle located between the P5 overhead panel in the flight compartment and the P33 relay panel located in the main equipment center.
• Changing the W2070 wire bundle located between the P5 overhead panel in the flight compartment and P37 relay panel located in the main equipment center.
• Changing the W1230 wire bundle at the P33 relay panel.
• Changing the W1270 wire bundle at the P37 relay panel.
• Doing a functional test of the left and right primary and secondary override pump control relays.
• Doing a pump reversal test of the left and right override fuel pumps.

We have also reviewed Boeing Temporary Revision (TR) 09-006, dated January 2007. Boeing TR 09-006 is published as Section 9 of the Boeing 757 MPD Document, D622N001-9, Revision January 2007 (hereafter referred to as “Revision January 2007 of the MPD”). Subsection G of Revision January 2007 of the MPD adds new fuel system AWL No. 28-AWL-26, which is a repetitive inspection of the power failed on protection system for the center tank fuel boost pumps to verify functional integrity.

Boeing Alert Service Bulletin 757-28A0105 specifies prior or concurrent accomplishment of BAE Systems Service Bulletin 233N3206-28-03, dated October 4, 2006. The BAE Systems service bulletin describes procedures for modifying the M10055 fuel control panel assembly, P/N 233N3206-( ), to provide protection from “uncommanded pump ON” situations. The modification includes rerouting the J2 connector wire bundles from the forward left main pump switch S2 to the left center pump switch S6, rerouting the J3 connector wire bundles from the forward right main pump switch S5 to the right center pump switch S7, and installing new tie clips to secure the rerouted wire bundles.

Accomplishing the actions specified in the service information is intended to adequately address the unsafe condition.

FAA's Determination and Requirements of the Proposed AD

We have evaluated all pertinent information and identified an unsafe condition that is likely to exist or develop on other airplanes of this same type design. For this reason, we are proposing this AD, which would require the following actions:

• Installation of an automatic shutoff system for the center tank fuel boost pumps.
• Installation of a placard in the airplane flight deck, if necessary. (Placards are necessary only for “mixed fleet operation,” which means that some airplanes in an operator's fleet are equipped with automatic shutoff systems while other airplanes are not.)
• Revisions to the Limitations and Normal Procedures sections of the AFM to advise the flightcrew of certain operating restrictions for airplanes equipped with an automated center tank fuel pump shutoff control.
• Revision to the AWLs section of the Instructions for Continued Airworthiness to incorporate AWL No. 28-AWL-20, which would require repetitive inspections of the automatic shutoff system for the center tank fuel boost pumps to verify functional integrity.
• Replacement of fuel control panel assembly P/N 233N3206-( ) with a modified fuel control panel assembly, installation of two secondary override pump control relays for the center tank fuel pumps in the P33 and P37 relays panels, and other specified actions.
• Concurrent modification of the M10055 fuel control panel assembly, P/N 233N3206-( ).
• Revision to the AWLs section of the Instructions for Continued Airworthiness to incorporate AWL No. 28-AWL-26, which would require repetitive inspections of the power failed on protection system for the center tank fuel boost pumps to verify functional integrity.

This proposed AD would also allow accomplishing the revision to the AWLs section of the Instructions for Continued Airworthiness in accordance with later revisions of the MPD as an acceptable method of compliance if they are approved by the Manager, Seattle Aircraft Certification Office (ACO), FAA.

Costs of Compliance

There are about 1,094 Model 757-200, -200CB, -200PF, and -300 series airplanes of the affected design in the worldwide fleet. The following table provides the estimated costs, at an average labor rate of $80 per hour, for U.S. operators to comply with this proposed AD. The estimated cost of parts in the following table depends on the configuration of an airplane.

Authority for This Rulemaking

Title 49 of the United States Code specifies the FAA's authority to issue rules on aviation safety. Subtitle I, Section 106, describes the authority of the FAA Administrator. Subtitle VII, Aviation Programs, describes in more detail the scope of the Agency's authority.

We are issuing this rulemaking under the authority described in Subtitle VII, Part A, Subpart III, Section 44701, “General requirements.” Under that section, Congress charges the FAA with promoting safe flight of civil aircraft in air commerce by prescribing regulations for practices, methods, and procedures the Administrator finds necessary for safety in air commerce. This regulation is within the scope of that authority because it addresses an unsafe condition that is likely to exist or develop on products identified in this rulemaking action.

Regulatory Findings

We have determined that this proposed AD would not have federalism implications under Executive Order 13132. This proposed AD would not have a substantial direct effect on the States, on the relationship between the national Government and the States, or on the distribution of power and responsibilities among the various levels of government.

For the reasons discussed above, I certify that the proposed regulation:

1. Is not a “significant regulatory action” under Executive Order 12866;

2. Is not a “significant rule” under the DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979); and

3. Will not have a significant economic impact, positive or negative, on a substantial number of small entities under the criteria of the Regulatory Flexibility Act. We prepared a regulatory evaluation of the estimated costs to comply with this proposed AD and placed it in the AD docket. See the ADDRESSES section for a location to examine the regulatory evaluation.

List of Subjects in 14 CFR Part 39

• Air transportation
• Aircraft
• Aviation safety
• Safety

The Proposed Amendment

Accordingly, under the authority delegated to me by the Administrator, the FAA proposes to amend 14 CFR part 39 as follows:

PART 39—AIRWORTHINESS DIRECTIVES

1. The authority citation for part 39 continues to read as follows:

Authority: 49 U.S.C. 106(g), 40113, 44701.